1. Technical Field
The present invention relates to an ink jet recording apparatus and a maintenance liquid for an ink jet recording apparatus.
2. Related Art
Since an ink jet recording apparatus ejects inks on recording media through fine nozzles provided in a head, the inks may be unsatisfactorily ejected by clogging of the fine nozzles due to thickening of the inks. In particular, when an aqueous ink composition is used as an ink, water as a main solvent of the ink is easily evaporated, and thus attempts have been made for preventing clogging due to drying and thickening of the inks by previously adding a high-boiling-point organic solvent such as glycerin to the aqueous ink composition. However, when an ink jet recording apparatus is not used over a long period of several days or more, there may occur defective ejection due to nozzle clogging of a head and a trouble due to drying and solidification of the ink in a moisture retention cap device of the head.
When an ink jet recording apparatus is not used for a long period of time, in order to suppress such defective ink ejection, it is proposed that drying of a head is prevented by replacing the ink in the head with a moisturizer (for example, Japanese Patent No. 3911928).
There is also proposed an ink jet recording apparatus in which under a non-printing state, drying of residual ink is suppressed by covering a head with a moisture retention cap device and supplying a moisturizer to a space in the moisture retention cap device in order to moisturize the head (for example, Japanese Unexamined Patent Application Publication No. 2003-334962).
As the moisturizer used in Japanese Patent No. 3911928 and Japanese Unexamined Patent Application Publication No. 2003-334962, a moisturizer containing only water and a moisturizer containing water and a high-boiling-point organic solvent such as glycerin are proposed.
However, the above-described moisturizer may be decayed by long-term use. In addition, when a moisture retention cap device containing the moisturizer to which a high-boiling-point organic solvent is added is allowed to stand for a long period of time, water is evaporated from the moisturizer in the moisture retention cap device, thereby concentrating the high-boiling-point organic solvent in the moisture retention cap. Therefore, water in an aqueous ink composition adhering to the head may be absorbed by the concentrated high-boiling-point organic solvent, thereby causing clogging of the head.
Alternatively, in an ink jet recording apparatus used for printing on non-ink-absorbing recording media such as plastic films, in order to improve the drying property of images formed on the recording media and to improve the fixability and abrasion resistance of images, it is necessary to decrease the amount of a high-boiling-point organic solvent, such as glycerin, contained in an ink composition. Therefore, in an ink jet recording apparatus using an ink composition improved in drying property, the aqueous ink composition having the high drying property is dried and solidified within a short time of several hour units in a flushing cap device of ejecting an ink for preventing nozzle clogging of a head or in a cap device for suction recovery for removing an ink in nozzles by suction, thereby causing an operation error.
That is, in comparison with the trouble of nozzle clogging in a head when an ink jet recording apparatus is allowed to stand without being used for a long period of time, a trouble due to drying and solidification of a residual ink in the maintenance cap device may occur more often within a short time when the residual ink is opened to air during an operation of the ink jet recording apparatus.
An ink jet recording apparatus provided with a plurality of ink jet heads has a problem that a cap is provided for each of the heads according to the applications of the caps.
In an ink jet recording apparatus provided with a plurality of ink jet heads, ejection conditions vary from head to head, and thus drying conditions of cap devices corresponding to the respective heads vary. For example, it is difficult to provide a detector on each of the cap devices and prevent drying by supplying a moisturizer.